Solid drawing composition

Abstract: The present invention provides a solid drawing composition comprising barium sulfate, the composition further comprising, as a barium dissolving inhibitor, at least one of (a) alkali metal sulfate, (b) beryllium sulfate, magnesium sulfate, calcium sulfate or strontium sulfate, (c) aluminum sulfate, (d) zinc sulfate, and (e) a double salt of said sulfates (a) to (d).

Description: The present invention relates to a solid drawing composition. Solid drawing compositions such as crayons, oil pastels, plastic crayons, colored pencils and the like generally comprise a wax, an extender pigment, a coloring pigment, a concentration adjuster, etc. Among these components, the extender pigment, concentration adjuster and the like may contain a predetermined amount of barium sulfate which enables the components to exhibit their functions effectively. However, in recent years, standards for safety of toys have been altered in Europe and the U.S. to tighten control. Consequently pigments and like materials containing specific soluble heavy metals have been legally regulated. Since such heavy metals include barium, the use of barium lake and like pigments is restricted. The control is strict especially in Europe. For example, under European Standards EN 71, the detected value of barium as measured by the prescribed method shall not exceed 500 ppm. At present, barium sulfate is not controlled under said regulation. However, the barium sulfate used as an extender pigment or as a concentration adjuster for a coloring pigment is slightly dissolved out so that a detected value of barium may exceed the prescribed level of 500 ppm, thereby posing a safety problem. On the other hand, currently, no material is superior to barium sulfate as an additive for an extender pigment, concentration adjuster and the like, and it is difficult to find out a substitute for barium sulfate. BR-A-8903495 (Chemical Abstracts, Vol. 715, No. 73024) discloses coloring compositions for plastics and rubbers which may contain, as pigment, a certain amount of, i.a., zinc sulfate and/or barium sulfate. An object of the present invention is to provide a solid drawing composition which contains barium sulfate and in which the barium is substantially not dissolved out. The present invention provides a solid drawing composition containing barium sulfate, the composition comprising, as a substance capable of inhibiting barium from dissolving out, a certain amount of at least one compound selected from (a) alkali metal sulfate, (b) beryllium sulfate, magnesium sulfate, calcium sulfate or strontium sulfate, (c) aluminum sulfate, (d) zinc sulfate, and (e) a double salt of said sulfates (a) to (d). The inventors found that when a specific sulfate is incorporated in a drawing composition containing barium sulfate, the barium can be significantly inhibited or prevented from dissolving out. The present invention has been accomplished based on this finding. The present invention is described below in detail. The solid drawing composition of the present invention is prepared by incorporating a predetermined amount of a specific sulfate and/or a double salt thereof into a conventional solid drawing composition such as a crayon, an oil pastel, a plastic crayon, a color pencil, etc. which contains barium sulfate as an ingredient of an extender pigment or the like. According to the invention, at least one of (a) alkali metal sulfate, (b) beryllium sulfate, magnesium sulfate, calcium sulfate or strontium sulfate, (c) aluminum sulfate, (d) zinc sulfate, and (e) a double salt of said sulfates (a) to (d) can be used as a substance capable of inhibiting barium from dissolving out (hereinafter referred to as "barium dissolution inhibitor"). Among them, preferable are sodium sulfate, potassium sulfate, calcium sulfate, magnesium sulfate, strontium sulfate, aluminum sulfate, zinc sulfate and a double salt of these sulfates (such as calcium sodium sulfate, magnesium potassium sulfate, calcium potassium sulfate, zinc potassium sulfate and the like). More preferable are calcium sulfate and the like. The amount of the barium dissolution inhibitor used according to the present invention is 0.001 to 20% by weight, preferably 0.2 to 1% by weight, based on the solid drawing composition. When the amount of the inhibitor exceeds 20% by weight, the resulting composition has poor drawability and thus is not suitable for use. If the amount is less than 0.001% by weight, the effect of inhibiting barium from dissolving out is unsatisfactory. Thus it is undesirable to use the inhibitor outside the said quantity range. The present invention also provides a solid drawing composition comprising a wax, an extender pigment, a coloring pigment and barium sulfate, the composition being characterized by containing 0.001 to 20% by weight of the composition of a substance capable of inhibiting barium from dissolving out, the substance being at least one of (a) alkali metal sulfate, (b) beryllium sulfate, magnesium sulfate, calcium sulfate or strontium sulfate, (c) aluminum sulfate, (d) zinc sulfate and (e) a double salt of said sulfates (a) to (d) (hereinafter called "second aspect of the invention"). Described below are the components other than barium dissolution inhibitor to be used in the solid drawing composition of the second aspect of the invention. Extender pigments which can be used in the second aspect of the invention include those heretofore known such as barium sulfate, calcium carbonate, magnesium carbonate, talc, clay, silica, kaolin and the like. The term "barium sulfate" used herein encompasses all of the barium sulfates such as precipitated barium sulfate, elutriated barium sulfate, etc. The amount of the extender pigment used is up to 70% by weight. If the amount of the extender pigment is more than 70% by weight, it is difficult to effect molding due to the increased viscosity of composition in a molten state, or poor drawability results. The lower limit of the extender pigment quantity is selected according to the formulation, desired properties and other factors of the solid drawing composition and is usually about 3% by weight. Coloring pigments which can be used in the second aspect of the invention include those containing barium sulfate used as a concentration adjuster. Known pigments can be used and include, for example, Fast Red 1547D, Z6 Violet J, Prussian Blue 660A (products of Dainichi Seika Color & Chemicals Manufacturing, Co., Ltd.), Ultramarine Blue C, Ultramarine Blue #8000, Ultramarine Blue PB-30 (products of Daiichi Kasei Kogyo), Red 7010, Symular Fast Yellow GF Conc. (products of Dai Nippon Ink & Chemicals Inc.) and the like. Also usable are conventional coloring pigments free from barium sulfate used as a concentration adjuster. Examples of such pigments are Cyanine Blue, Cyanine Green, Hansa Yellow, Quinacridone Red, Naphthol Red, Watchung Red, Dioxazine Violet, Carbon Black, titanium dioxide, Prussian Blue, Perinone Orange, Ultramarine Blue, fluorescent pigments, etc. The amount of these coloring pigments used is about 0.5 to about 40% by weight based on the drawing composition. If the amount of the coloring pigment is more than 40% by weight, a sharp color cannot be produced, or it is difficult to effect molding due to the increased viscosity of composition in a molten state, or poor drawability results. If the amount is less than 0.5% by weight, a satisfactory color can not be provided. In the solid drawing composition of the second aspect of the invention, at least one of the extender pigment and coloring pigment contains barium sulfate. Barium sulfate may be contained as another component in the solid drawing composition of the second invention. Waxes conventionally used for known drawing compositions can be used as such in the second invention. Examples of useful waxes are ketone wax, animal based hardened oil, vegetable based hydrogenated oil, paraffin wax, microcrystalline wax, polyethylene wax, liquid paraffin, aliphatic amide, poly α-olefin, beeswax, carnauba wax, Japan wax, etc. The amount of the wax used is about 20 to about 95% by weight. If the amount of the wax is less than 20% by weight, it is difficult to effect molding due to the increased viscosity of the composition in a molten state, or poor drawability results. If the amount is more than 95% by weight, the obtained drawing composition has reduced strength and the wax is likely to adhere to the hand, etc. The present invention further provides a solid drawing composition comprising a wax, an extender pigment, a coloring pigment, an olefin polymer other than said wax and barium sulfate, the composition being characterized by containing 0.001 to 20% by weight of the composition of a substance capable of inhibiting barium from dissolving out, the substance being at least one of (a) alkali metal sulfate, (b) beryllium sulfate, magnesium sulfate, calcium sulfate or strontium sulfate, (c) aluminum sulfate, (d) zinc sulfate, and (e) a double salt of said sulfates (a) to (d) (hereinafter called "third aspect of the invention"). Described below are the components other than barium dissolution inhibitor to be used in the solid drawing composition of the third aspect of the invention. The extender pigments exemplified above for the second aspect of the invention can be used in the third aspect of the invention. Further, calcium stearate, zinc stearate and the like are also usable. The amount of the extender pigment used is up to about 50% by weight. If the amount of the extender pigment is more than 50% by weight, it is difficult to effect molding due to the increased viscosity of composition in a molten state, or poor drawability results. The lower limit of the extender pigment quantity is selectable according to the formulation, desired properties and other factors of the solid drawing composition and is usually about 1% by weight. The coloring pigments containing or not containing barium sulfate used in a concentration adjuster can be used in the third aspect of the invention as well as in the second aspect of the invention. The amount of the coloring pigment used may be the same as in the second aspect of the invention. In the solid drawing composition of the third aspect of the invention, at least one of the extender pigment and coloring pigment contains barium sulfate. Barium sulfate may be contained as another component in the solid drawing composition of the third aspect of the invention. The wax to be used in the third aspect of the invention may be those exemplified above for the second aspect of the invention. The amount of the wax used is about 5 to about 70% by weight. If the amount of the wax is less than 5% by weight, it is difficult to effect molding due to the increased viscosity of the composition in a molten state, or poor drawability results. If the amount is more than 70% by weight, the resulting drawing composition has reduced strength and the wax is likely to adhere to the hand, etc. The olefin polymer other than said wax to be used is not specifically limited, and can be, for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethylacrylate copolymer and the like. The amount of the olefin polymer used is about 5 to about 60% by weight. If the amount of the olefin polymer is less than 5% by weight, the resulting drawing composition has reduced strength or is likely to adhere to the hand, etc. If the amount is more than 60% by weight, a decreased coloration effect is produced. Also usable are butyl stearate, polyethylene glycol and like additives used in conventional drawing compositions. The amount of such additive used is about 0.5 to about 30% by weight. If less than 0.5% by weight of the additive is used, poor drawability results, whereas if more than 50% by weight thereof is used, the obtained drawing composition has reduced strength. The solid drawing composition of the present invention can be prepared by processes for preparing conventional solid drawing compositions, for example, by a process comprising adding a pigment, a barium dissolution inhibitor and other components to a molten wax, stirring the mixture, dispersing the mixture with a dispersing device such as single-roll mill, three-roll mill, Henschel mixer, kneader and the like and placing the composition into a molding die. The solid drawing composition of the present invention can reduce the amount of soluble barium without impairing its drawability, strength and other properties, and can produce remarkable effects in respect of safety and so on. Examples Examples, Comparative Examples and Test Example are given below to illustrate the present invention in greater detail. In Test Example, the amount of dissolved-out barium was measured according to the method defined in European Standards EN 71, part 3. A drawability test was conducted by holding a molded product of the solid drawing composition in hand and drawing a line on drawing paper. The results were evaluated according to the following criteria. A: Drawn with resistance. B: Drawn smoothly without resistance. Example 1 Sample No. 1 of a solid drawing composition (oil pastel) with the formulation shown in Table 1 was prepared. Sample No. 1' was also prepared for comparison using calcium carbonate in lieu of calcium sulfate. Component Amount (wt.part) Fast Red 1547D (containing about 20% of barium sulfate) 5 Permanent Red FGR (product of Hoechst AG, Naphthol Red) 10 Calcium sulfate 13 Calcium carbonate 39 Highly hydrogenated beef tallow 15 Paraffin 135° F 3 Liquid paraffin 15 Example 2 Sample No. 2 of a solid drawing composition (crayon) with the formulation shown in Table 2 was prepared. Sample No. 2' was also prepared for comparison using calcium carbonate in lieu of potassium sulfate. Component Amount (wt.part) Dioxazine violet 4 Titanium dioxide 12 Potassium sulfate 0.5 Barium sulfate 3 Calcium carbonate 25 Talc 18 Extremely hydrogenated beef tallow 18.5 Dialen® 30 (product of Mitsubishi Chemical Industries, Ltd., poly α-olefin) 4 Liquid paraffin 15 Example 3 Sample No. 3 of a solid drawing composition (oil pastel) with the formulation shown in Table 3 was prepared. Sample No. 3' was also prepared for comparison using calcium carbonate in lieu of magnesium sulfate. Component Amount (wt.part) Ultramarine Blue PB-30 (containing a few percent of barium sulfate) 20 Magnesium carbonate 6 Calcium carbonate 23 Aluminum sulfate 1 Microcrystalline wax 5 Carnauba wax 18 Petrolatum 7 Liquid paraffin 20 Example 4 Sample No. 4 of a solid drawing composition (oil pastel) with the formulation shown in Table 4 was prepared. Sample No. 4' was also prepared for comparison using calcium carbonate in lieu of aluminum sulfate and calcium sulfate. Component Amount (wt.part) Z6 violet J (containing about 30% of barium sulfate) 10 Hostaperm® Red E3B (product of Hoechst AG, Quinacridone Red) 7 Magnesium carbonate 20 Aluminum sulfate 13 Calcium sulfate 6 Neowax® L (Product of Yasuhara Chemical, polyethylene wax) 12 Japan wax 10 Liquid paraffin 22 Comparative Example 1 Comparative Sample No. 1 of a solid drawing composition (oil pastel) with the formulation shown in Table 5 was prepared. Component Amount (wt.part) Fast Red 1547D (containing about 20% of barium sulfate) 5 Permanent Red FGR (product of Hoechst AG, Naphthol Red) 10 Calcium sulfate 30 Calcium carbonate 22 Extremely hydrogenated beef tallow 15 Paraffin 135°F 3 Liquid paraffin 15 Example 5 Sample No. 5 of a solid drawing composition (plastic crayon) with the formulation shown in Table 6 was prepared. Sample No. 5' was also prepared for comparison using calcium carbonate in lieu of calcium sulfate. Component Amount (wt.part) Hostaperm® Red F5RK (product of Hoechst AG, Naphthol Red) 10 Barium sulfate 10 Calcium sulfate 2 Calcium stearate 10 Microcrystalline wax 13 High-pressure process polyethylene 30 Ethylene-vinyl acetate copolymer 10 PEG 6000 7 Liquid paraffin 8 Example 6 Sample No. 6 of a solid drawing composition (plastic crayon) with the formulation shown in Table 7 was prepared. Sample No. 6' was also prepared for comparison using calcium carbonate in lieu of magnesium sulfate and calcium sulfate. Component Amount (wt.part) Prussian Blue 660A (containing about 4% of barium sulfate) 9 Aluminum sulfate 10 Calcium stearate 13 High-pressure process polyethylene 30 Stearic acid amide 13 Ethylene-vinyl acetate copolymer 10 PEG 6000 7 Liquid paraffin 8 Example 7 Sample No. 7 of a solid drawing composition (plastic crayon) with the formulation shown in Table 8 was prepared. Sample No. 7' was also prepared for comparison using calcium carbonate in lieu of calcium sulfate and aluminum sulfate. Component Amount (wt.part) Ultramarine Blue PB-30 (containing a few percent of barium sulfate) 10 Calcium sulfate 5 Aluminum sulfate 10 Calcium stearate 13 High-pressure process polyethylene 27 Distearyl ketone 10 Ethylene-vinyl acetate copolymer 10 Paraffin 115°F 7 Butyl stearate 8 Example 8 Sample No. 8 of a solid drawing composition (plastic crayon) with the formulation shown in Table 9 was prepared. Sample No. 8' was also prepared for comparison using calcium carbonate in lieu of calcium sulfate and aluminum sulfate. Component Amount (wt.part) Fast Red 1547D (containing about 20% of barium sulfate) 10 Potassium sulfate 18 Zinc stearate 8 High-pressure process polyethylene 26 Fischer-Tropsch wax 13 Ethylene-ethyl acrylate copolymer 10 PEG 6000 7 Liquid paraffin 8 Example 9 A sample No. 9 of a solid drawing composition (oil pastel) with the formulation shown in Table 10 was prepared. Sample No. 9' was also prepared for comparison using calcium carbonate in lieu of sodium sulfate. Component Amount (wt.part) Ultramarine Blue #8000 (containing a few percent of barium sulfate) 12 Cyanine blue 5 Sodium sulfate 13 Calcium carbonate 37 Stearic acid amide 8 Paraffin 115° 10 Liquid paraffin 15 Example 10 Sample No. 10 of a solid drawing composition (crayon) with the formulation shown in Table 11 was prepared. Sample No. 10' was also prepared for comparison using calcium carbonate in lieu of zinc sulfate. Component Amount (wt.part) Dioxazine violet 6 Zinc oxide 8 Zinc sulfate 0.7 Barium sulfate 5 Calcium carbonate 11 Talc 14 Carnauba wax 21.3 Paraffin 135° 19 Liquid paraffin 15 Example 11 Sample No. 11 of a solid drawing composition (crayon) with the formulation shown in Table 12 was prepared. Sample No. 11' was also prepared for comparison using calcium carbonate in lieu of strontium sulfate. Component Amount (wt.part) Ultramarine Blue PB-30 (containing a few percent of barium sulfate) 15 Talc 12 Calcium carbonate 14 Strontium sulfate 5 Microcrystalline wax 13 Distearyl ketone 21 Petrolatum 4 Liquid paraffin 16 Example 12 Sample No. 12 of a solid drawing composition (oil pastel) with the formulation shown in Table 13 was prepared. Sample No. 12' was also prepared for comparison using calcium carbonate in lieu of calcium potassium sulfate. Component Amount (wt.part) Ultramarine Blue PB-30 (containing a few percent of barium sulfate) 18.5 Kaolin 6 Magnesium carbonate 20 Calcium potassium sulfate 1.5 Beeswax 5 Distearyl ketone 21 Petrolatum 4 Liquid paraffin 24 Example 13 Sample No. 13 of a solid drawing composition (plastic crayon) with the formulation shown in Table 14 was prepared. Sample No. 13' was also prepared for comparison using calcium carbonate in lieu of sodium sulfate. Component Amount (wt.part) Hostaperm® Red F5RK (Hoechst AG, Naphthol Red) 10 Barium sulfate 7 Sodium sulfate 5 Calcium stearate 10 High-pressure process polyethylene 22 Stearic acid amide 13 Ethylene-vinyl acetate copolymer 10 PEG 6000 15 Liquid paraffin 8 Example 14 Sample No. 14 of a solid drawing composition (plastic crayon) with the formulation shown in Table 15 was prepared. Sample No. 14' was also prepared for comparison using calcium carbonate in lieu of zinc sulfate. Component Amount (wt.part) Vulcan Orange 6 Barium sulfate 7 Zinc sulfate 1 Calcium stearate 10 High-pressure process polyethylene 26 Stearic acid amide 10 Ethylene-vinyl acetate copolymer 15 PEG 6000 15 Butyl stearate 10 Example 15 Sample No. 15 of a solid drawing composition (plastic crayon) with the formulation shown in Table 16 was prepared. Sample No. 15' was also prepared for comparison using calcium carbonate in lieu of strontium sulfate. Component Amount (wt.part) Cyanine Green 4 Barium sulfate 13 Strontium sulfate 3 Aluminum stearate 12 High-pressure process polyethylene 26 Ethylene-vinyl acetate copolymer 11 Beeswax 15 Liquid paraffin 16 Example 16 Sample No. 16 of a solid drawing composition (plastic crayon) with the formulation shown in Table 17 was prepared. Sample No. 16' was also prepared for comparison using calcium carbonate in lieu of zinc potassium sulfate. Component Amount (wt.part) Symular Fast Yellow GF Conc. (containing a few percent of barium sulfate) 10 Titanium dioxide 5 Barium sulfate 9 Zinc potassium sulfate 4 Zinc stearate 10 High-pressure process polyethylene 27 Ethylene-ethyl acrylate copolymer 8 Japan wax 12 Liquid paraffin 15 Comparative Example 2 Comparative Sample No. 2 of a solid drawing composition (plastic crayon) with the formulation shown in Table 18 was prepared. Component Amount (wt.%) Z6 violet J (containing about 30% of barium sulfate) 7 Magnesium sulfate 24 Calcium stearate 10 High-pressure process polyethylene 30 Ethylene-vinyl acetate copolymer 10 Paraffin 130°F 7 Microcrystalline wax 4 Butyl stearate 8 Test Example 1 Using the above-obtained Samples Nos. 1 to 16 and Nos. 1' to 16' and Comparative Samples Nos. 1 and 2, the amount of dissolved-out barium was measured and a drawability test was conducted. The results are shown in Table 19. Sample No. Amount of soluble barium (ppm) Drawability 1 10 A 2 23 A 3 7 A 4 18 A 5 4 A 6 8 A 7 13 A 8 10 A 9 10 A 10 12 A 11 7 A 12 15 A 13 9 A 14 20 A 15 13 A 16 18 A 1' 510 A 2' 490 A 3' 536 A 4' 570 A 5' 508 A 6' 516 A 7' 521 A 8' 494 A 9' 480 A 10' 523 A 11' 502 A 12' 554 A 13' 511 A 14' 535 A 15' 499 A 16' 504 A Comp. 1 12 B Comp. 2 8 B It is apparent from the results shown in Table 19 that a considerable amount of barium was dissolved out from Samples No. 1' to 16' not containing a barium dissolution inhibitor, and Comparative Samples Nos. 1 and 2 containing an excess amount of a barium dissolution inhibitor exhibited poor drawability. In contrast, Samples Nos. 1 to 16, i.e., the drawing compositions of the present invention, effectively inhibited barium from dissolving out without impairing the drawability.

Claims: A solid drawing composition containing barium sulfate, the composition comprising, as a barium dissolution inhibitor, 0.001 to 20% by weight of the composition of at least one compound selected from (a) alkali metal sulfate, (b) beryllium sulfate, magnesium sulfate, calcium sulfate or strontium sulfate, (c) aluminum sulfate, (d) zinc sulfate, and (e) a double salt of said sulfates (a) to (d). The solid drawing composition as defined in claim 1 wherein the barium dissolution inhibitor is at least one compound selected from sodium sulfate, potassium sulfate, calcium sulfate, magnesium sulfate, strontium sulfate, aluminum sulfate, zinc sulfate, calcium sodium sulfate, magnesium potassium sulfate, calcium potassium sulfate and zinc potassium sulfate. The solid drawing composition as defined in claim 1 wherein the amount of the barium dissolution inhibitor is 0.2 to 1% by weight of the composition. The solid drawing composition as defined in any one of claims 1 to 3 which comprises a wax, an extender pigment and a coloring pigment. The solid drawing composition as defined in any one of claims 1 to 3 which comprises a wax, an extender pigment, a coloring pigment and an olefin polymer other than said wax.

Inventors: YAMAMOTO RYUZO, YAMAMOTO, RYUZO
Applicants: SAKURA COLOR PROD CORP, SAKURA COLOR PRODUCTS CORPORATION
Application year: 1994
Main classification: C09D13
IPC codes: C08K3, C09D13, B43K19